1. Field of the Invention
This invention relates generally to slide fasteners and particularly to a bottom end stop therefor which is adapted to restrict the movement of a slider at a bottom or lower end of the fastener.
2. Prior Art
There are known various forms of a row of coupling elements attached to a pair of stringer tapes, which elements are formed by injection molding of a synthetic resin into discrete individual structures each having a coupling head portion with an engaging recess in front, a barrel portion and a heel portion. A row of such coupling elements is mounted with their barrel portions astride a longitudinal edge of each of a pair of stringer tapes so that their coupling head portions protrude beyond the tape edge for interengagement with corresponding head portions on an opposed companion stringer tape. More specifically, the coupling element includes a narrow neck portion intermediate between the coupling head portion and the barrel portion and a pair of shoulder portions located on opposite sides of the neck portion and having respective engaging ribs engageable with the engaging recesses in the neighboring elements.
A typical example of a bottom end stop for use with coupling elements of the above construction is disclosed in Japanese Laid Open Utility Model Publication No. 56-37605, which end stop is attached to a pair of stringer tapes at one end thereof in such a manner that it merely overlies and joint part of both the coupling head and heel portions of a terminal one of the coupling elements.
Slide fasteners having the above described coupling elements may be effective for eliminating separation or a so-called "chain crack" of the two interengaged stringers which would take place when the fastener is subjected to upwardly directed thrust or stresses exerted for example from inside a bag fully loaded and tightly closed by the slide fastener. The prior art bottom end stop has a drawback in that since it is simply connected in overlying relation to a terminal or endmost coupling element, the "chain crack" is prone to occur at and from between that particular terminal element and the end stop when the slide fastener receives an external thrust force tending to split the two engaged stringers of the fastener.
It may be theoretically possible to preclude the problem of "chain crack" with the afore-mentioned type of slide fastener by providing a bottom end stop wilt an extra portion engageable with the engaging rib of the terminal coupling element. However, in as much as such end stops are mostly injection-molded, a hot melt of plastics material in the cavity of the mold tends to leak from the engaging recess in the coupling element and fill up between the coupling head portion of a terminal element and the neck portion of an adjoining coupling element, rendering it difficult to open or close the fasteners.